There is a clear and immediate need for a more effective therapy for advanced ovarian cancer. To address this need, our long-term goal is to develop a nanotherapy for advanced-stage metastatic ovarian cancer that effectively manages the cancer, resulting in a longer, healthy life. The objective of the proposed experiments is to introduce modifications to a promising new class of cationic, biodegradable poly(2-amino ester) polymers that result in efficient, targeted nanoparticle-delivery of DNA to ovarian tumor cells. The proposed experiments test the hypothesis that intraperitoneal administration of polymeric nanoparticles designed to target the delivery of DNA encoding so-called suicide genes to ovarian cancer cells will effectively kill the cells, resulting in ovarian tumor regression. We will modify polymers in three ways, aiming to enhance their ability to target DNA delivery to ovarian cancer cells and to improve their resistance to inactivation by serum. One approach will be to pegylate polymers and conjugate them to one of two single chain variable antibody fragments (scFvs) having reactivity to proteins found on the surface of ovarian tumor cells, or to folic acid. The second approach will be to complex DNA poly(2-amino ester)-nanoparticles with scFv- or folic acid-conjugated poly(acrylic acid). The third approach will be to make combinatorial end-modifications to the structure of poly(2-amino ester)s. We will use a high-throughput cell-based transfection assay to identify the modified polymers imparting the highest degree of serum resistance and DNA delivery. We will then test the effectiveness of selected polymer formulations in three in vivo mouse models: a transgenic model for ovarian cancer, a sygeneic mouse/tumor cell model, and a human tumor cell xenograft model. In addition to targeting DNA delivery to ovarian cancer cells, we aim to target gene expression using ovarian-specific promoter sequences. We will use non-invasive imaging technologies (bioluminescence and microCT) to assess longitudinally the response of tumors to the nanoparticle-delivers DT-A therapy. In addition, we will determine the effect of this therapy on life span and determine whether the therapy results in non-specific toxicity. There are currently no effective therapies for advanced-stage ovarian cancer patients. Our expectation is that the innovative use of nanoparticles to target delivery of suicide genes to ovarian cancer cells, combined with a strategy for targeting gene expression to these cells, will lead to an effective treatment for this deadly disease. While we focus here on the development of a new therapy for ovarian cancer, this study will help establish the utility of nanoparticles for gene therapy and pave the way for their broader application for treating additional types of cancer and other diseases. Project Narrative: Poly(2-amino ester)s is cationic, biodegradable polymers that show great promise as non-viral vectors for the delivery of therapeutic DNA to cancer cells. There are currently no effective therapies for advanced-stage ovarian cancer patients that either do not respond to initial therapy or those with recurrent disease. The purpose of this study is to introduce modifications to poly(2-amino ester)s that result in efficient, targeted nanoparticle-delivery of DNA encoding suicide genes to ovarian tumor cells following intraperitoneal administration. Targeted nanotherapy, used alone or as an adjuvant therapy, should lead to a more effective treatment for patients with metastatic ovarian cancer.